Knowledge Resource Center for Ecological Environment in Arid Area
DOI | 10.1029/1999JD900923 |
Wavelength dependence of the optical depth of biomass burning, urban, and desert dust aerosols | |
Eck, TF; Holben, BN; Reid, JS; Dubovik, O; Smirnov, A; O’Neill, NT; Slutsker, I; Kinne, S | |
通讯作者 | Eck, TF |
来源期刊 | JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES |
ISSN | 2169-897X |
EISSN | 2169-8996 |
出版年 | 1999 |
卷号 | 104期号:D24页码:31333-31349 |
英文摘要 | The Angstrom wavelength exponent alpha, which is the slope of the logarithm of aerosol optical depth (tau(a)) versus the logarithm of wavelength (lambda), is commonly used to characterize the wavelength dependence of tau(a) and to provide some basic information on the aerosol size distribution. This parameter is frequently computed from the spectral measurements of both ground-based sunphotometers and from satellite and aircraft remote sensing retrievals. However, spectral variation of alpha is typically not considered in the analysis and comparison of values from different techniques. We analyze the spectral measurements of tau(a) from 340 to 1020 nm obtained from ground-based Aerosol Robotic Network radiometers located in various locations where either biomass burning, urban, or desert dust aerosols are prevalent. Aerosol size distribution retrievals obtained from combined solar extinction and sky radiance measurements are also utilized in the analysis. These data show that there is significant curvature in the ln tau(a) versus ln lambda relationship for aerosol size distributions dominated by accumulation mode aerosols (biomass burning and urban). Mie theory calculations of alpha for biomass burning smoke (for a case of aged smoke at high optical depth) agree well with observations, confirming that large spectral variations in a are due to the dominance of accumulation mode aerosols, A second order polynomial fit to the ln tau(a) versus ln lambda data provides excellent agreement with differences in tau(a) of the order of the uncertainty in the measurements (similar to 0.01-0.02). The significant curvature in ln tau(a) versus ln lambda for high optical depth accumulation mode dominated aerosols results in alpha values differing by a factor of 3-5 from 340 to 870 nm. We characterize the curvature in ln tau(a) versus ln lambda by the second derivative alpha’ and suggest that this parameter be utilized in conjunction with alpha to characterize the spectral dependence of tau(a). The second derivative of ln tau(a) versus ln lambda gives an indication of the relative influence of accumulation mode versus coarse mode particles on optical properties. |
类型 | Article |
语种 | 英语 |
国家 | USA ; Canada |
收录类别 | SCI-E |
WOS记录号 | WOS:000084692900032 |
WOS关键词 | SIZE DISTRIBUTION ; VARIABILITY ; VEGETATION ; EXTINCTION ; MODEL |
WOS类目 | Meteorology & Atmospheric Sciences |
WOS研究方向 | Meteorology & Atmospheric Sciences |
资源类型 | 期刊论文 |
条目标识符 | http://119.78.100.177/qdio/handle/2XILL650/137698 |
作者单位 | (1)NASA, Goddard Space Flight Ctr, Sci Syst & Applicat Inc, Greenbelt, MD 20771 USA;(2)NASA, Goddard Space Flight Ctr, Raytheon ITSS, Greenbelt, MD 20771 USA;(3)NASA, Goddard Space Flight Ctr, Biospher Sci Branch, Greenbelt, MD 20771 USA;(4)Univ Maryland, NASA, Goddard Space Flight Ctr, Greenbelt, MD 20771 USA;(5)Space & Naval Warfare Syst Ctr, Tropospher Branch, San Diego, CA USA;(6)Univ Sherbrooke, Ctr Applicat & Rech Teledetect, Sherbrooke, PQ J1K 2R1, Canada |
推荐引用方式 GB/T 7714 | Eck, TF,Holben, BN,Reid, JS,et al. Wavelength dependence of the optical depth of biomass burning, urban, and desert dust aerosols[J],1999,104(D24):31333-31349. |
APA | Eck, TF.,Holben, BN.,Reid, JS.,Dubovik, O.,Smirnov, A.,...&Kinne, S.(1999).Wavelength dependence of the optical depth of biomass burning, urban, and desert dust aerosols.JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES,104(D24),31333-31349. |
MLA | Eck, TF,et al."Wavelength dependence of the optical depth of biomass burning, urban, and desert dust aerosols".JOURNAL OF GEOPHYSICAL RESEARCH-ATMOSPHERES 104.D24(1999):31333-31349. |
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